Exterior mirror assembly with actuator

ABSTRACT

An exterior rearview mirror assembly for a vehicle includes a mounting portion mountable at a side of a vehicle, a mirror head portion adjustably mounted at the mounting portion, and a reflective element at the mirror head portion. An actuator is operable to impart pivotal movement of the mirror head portion relative to the mounting portion and about a generally vertical pivot axis to pivotally adjust the mirror head portion relative to the side of the vehicle at which the mounting portion is mounted. The actuator comprises at least two motors and the motors are operable in tandem to cooperatively rotatably drive a common gear of a gear system to pivot the mirror head portion relative to the mounting portion. Responsive to a determination of the rotational movement being below a threshold speed, a shutoff circuit deactivates at least one of the motors irrespective of current draw by the motor.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/663,542, filed Oct. 30, 2012, now U.S. Pat. No. 9,067,541,which claims the benefits of U.S. provisional applications, Ser. No.61/665,504, filed Jun. 28, 2012, and Ser. No. 61/553,537, filed Oct. 31,2011, which are hereby incorporated herein by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates generally to exterior rearview mirrorassemblies and, more particularly, to an exterior rearview mirrorassembly that is adjustable relative to the side of the vehicle to whichit is mounted.

BACKGROUND OF THE INVENTION

It is known to provide a vehicular exterior rearview mirror assemblythat has a mirror head having a mirror casing that is adjustablerelative to a mirror mounting portion at the side of the vehicle towhich the mirror assembly is mounted. The mirror assembly may comprise apowerfold assembly where the mirror head is adjusted or pivoted relativeto the vehicle via an actuator disposed at the mirror mounting portionand/or mirror head. Examples of adjustable or powerfold rearview mirrorassemblies and actuators are described in U.S. Pat. Nos. 7,314,285;7,267,449; 7,159,992; 7,093,946; 6,312,135; 6,243,218; and 5,703,731,which are hereby incorporated herein by reference in their entireties.As the size and/or electrical content of exterior rearview mirrorassemblies is increased (such as for pickup trucks and the like), theweight of the mirror head portion likewise is increased, and a largeractuator motor or multiple gears or gear elements are required toprovide sufficient torque output to pivot the mirror head via anactuator motor, with such multiple gears adding to the cost andcomplexity of the actuator assemblies.

SUMMARY OF THE INVENTION

The present invention provides an exterior rearview mirror assembly thathas a mirror head portion (having a reflective element and mirrorcasing) that is adjustable via an actuator that moves or pivots the headportion sidewardly relative to a mounting arm or base portion of themirror assembly. The actuator comprises a pair of motors that arecooperatively operable to rotatably drive a common gear of the actuatorto pivot the head portion relative to the mounting arm or base portion.

According to an aspect of the present invention, an exterior rearviewmirror assembly for a vehicle includes a mounting portion mounted to aside of a vehicle, a mirror head portion, a reflective element supportedat or fixedly attached at or to the mirror head portion, and anactuator. The actuator is operable to impart pivotal movement of thehead portion relative to the mounting portion to adjust the head portionand reflective element relative to the side of the vehicle at which themounting portion is mounted. The actuator comprise a plurality of gearsor gear elements that are rotatably driven via a pair of motors, wherebythe pair of motors, such as responsive to a user input or the like,cooperate to rotatably drive a common drive gear that, when rotated,imparts rotational movement of another gear element and/or an attachingelement that attaches to either the mirror head portion or the mountingportion, whereby such rotational movement in turn pivots or rotates themirror head portion relative to the mounting portion of the mirrorassembly.

Therefore, the dual motor actuator of the present invention includes twomotors engaged with and driving a common gear. The dual motorarrangement provides increased output torque at the actuator whilemaintaining the tooth load (at the interface between the motor's outputshaft or output gear and the common gear) on the first or common gearthe same as for a single actuator motor (and thus allows for use oftypical drive gears without having to implement stronger more robustgears to handle increased output torque of a larger single motor). Theactuator of the present invention thus may be used in any mirrorapplication that requires high torque output to pivot large and/or heavymirror head portions, such as for trailer towing power fold mirrorassemblies and/or power extend mirror assemblies and/or the like.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear view of an exterior rearview mirror assembly inaccordance with the present invention;

FIG. 2 is an exploded perspective view of an actuator of an exteriorrearview mirror assembly of the present invention;

FIG. 3 is a side elevation of the actuator of FIG. 2;

FIG. 4 is top plan view of the actuator of FIG. 2;

FIG. 5 is another top plan view of the actuator of the presentinvention, shown with the upper casing portion removed to showadditional details;

FIG. 6 is a perspective view of the actuator of FIG. 5;

FIG. 7 is a perspective view of the motors and gear train of theactuator of the present invention, shown with the casing removed to showadditional details;

FIG. 8 is another perspective view of the motors and gear train of theactuator of FIG. 7, shown with bearings and motor spacers in accordancewith the present invention;

FIG. 9 is a schematic of a run detection shutoff circuit for theactuator motors of the present invention;

FIG. 10 is a functional block diagram of a run detection shutoff circuitfor the actuator motors of the present invention;

FIG. 11 is an exploded perspective view of another actuator of anexterior rearview mirror assembly of the present invention;

FIG. 12 is a side elevation of the actuator of FIG. 11;

FIG. 13 is another side elevation of the actuator of FIG. 11;

FIG. 14 is a top plan view of the actuator of FIG. 11;

FIG. 15 is another top plan view of the actuator of FIG. 11, shown withthe upper cover portion removed;

FIG. 16 is a perspective view of the actuator of FIG. 15; and

FIG. 17 is a perspective view of the motors and gears of the actuator ofFIGS. 11-16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and the illustrative embodiments depictedtherein, an exterior rearview mirror assembly 10 for a vehicle 11includes a mirror reflector or reflective element 12 received in and/orsupported at or by a mirror shell or casing or head portion 14 that ismovably mounted to a mounting arm or base or portion or actuatorreceiver or housing 16 via an actuator assembly or adjustment device 18(FIGS. 1-4). Mounting arm 16 of mirror assembly 10 is mounted at theside 11 a of a host or subject vehicle 11, with the reflective element12 providing a rearward field of view along the respective side of thevehicle to the driver of the vehicle. Actuator assembly 18 is receivedor disposed at least partially in mounting arm 16 (and/or at or at leastpartially in a side portion of the vehicle and/or at or at leastpartially in the mirror head portion of the mirror assembly) and isoperable to pivot the mirror head portion 14 relative to the mountingarm 16 to adjust the mirror head between a rearward viewing position ororientation, where the mirror head portion and mirror reflective elementare positioned so as to provide a rearward field of view to the driverof the vehicle (such as shown in FIG. 1), and a folded or stowedposition (not shown), where the mirror head and reflective element areoriented generally along the side of the vehicle, as discussed below.The actuator assembly 18 includes at least two electrical drive motors20, 22, which are cooperatively operable to rotatably drive a commondrive gear 24 of a gear train or gear assembly 26 to pivot the mirrorhead portion 14 about a generally vertical pivot axis to adjust themirror head portion 14 relative to the mounting arm 16, as alsodiscussed below.

Mounting base or portion or arm 16 is fixedly mounted at a side portionof a vehicle, and comprises an elongated arm or body or member thatextends outwardly from a vehicle attachment end, with the head portion14 being pivotally or adjustably disposed at an outer or mirrorattachment end of mounting arm 16. The mounting arm 16 comprises agenerally hollow portion or cavity for receiving actuator assembly 18therein, and a mirror head attaching portion 28 of actuator assembly 18is disposed at the mirror attachment end of mounting arm 16 when theactuator assembly 18 is received in the mounting arm 16. Although shownas extending generally laterally outwardly from a vehicle mounting areaat the side of the vehicle, the mounting arm or mounting portion oractuator housing may otherwise extend from the vehicle (such asgenerally upwardly and outwardly from the side of the vehicle) or may beat least partially recessed or received in or at the side of thevehicle, while remaining within the spirit and scope of the presentinvention.

The mirror head portion 14 is attached to mirror head attaching portion28 of actuator assembly 18 via any suitable means. In the illustratedembodiment, a lower inboard region or portion of mirror head portion 14is fixedly attached to an attaching ring or element or portion 28 a ofmirror head attaching portion 28 of actuator assembly 18, such as via afastener or fasteners or via a snap-together configuration or via anadhesive or via any other suitable mechanical or bonding means. Mirrorhead portion 14 may comprise any suitable shape, such as an aerodynamicshape or form, and may be selectively sized for the particularapplication. Optionally, the mirror head portion 14 may house or supportone or more mirror or vehicle accessories, such as exterior lights orblind spot indicators or turn signal indicators or the like (such asthose discussed below), while remaining within the spirit and scope ofthe present invention.

Optionally, the reflective element may attach to a mounting surface ofor at the mirror head portion or the reflective element may be receivedin or partially received in a receiving structure or bezel structure atthe mirror head portion (and may be attached at a mounting plate orbacking plate that may be adjustably mounted or disposed in the mirrorcasing and that may be adjustable via a powered mirror reflectiveelement adjustment actuator to allow for adjustment of the mirrorreflective element relative to the mirror casing to establish a desiredrearward field of view to the driver of the vehicle), while remainingwithin the spirit and scope of the present invention. Reflective element12 may comprise a single pane reflective element or an electro-opticreflective element (such as an electrochromic reflective element) withfront and rear substrates and an electro-optic medium sandwichedtherebetween, such as discussed below. Optionally, the reflectiveelement may have a fillet or rounded edge or radius established aroundits perimeter edge, such as to meet safety regulations is exposed, andmay not include a bezel portion that encompasses the perimeter edge ofthe reflective element when the reflective element is attached to themirror head portion 14 (such as described in U.S. patent applicationSer. No. 13/023,747, filed Feb. 9, 2011, now U.S. Pat. No. 8,915,601,which is hereby incorporated herein by reference in its entirety). Thereflective element 12 is adjustably mounted or supported at or in orpartially in mirror head portion 14, such as via a reflective elementactuator or the like.

Actuator assembly 18 is operable to pivot or adjust mirror head portion14 relative to mounting arm 16 such that the mirror head portion 14 isadjusted relative to mounting arm 16 about a generally vertical pivotaxis. Actuator assembly 18 includes a housing portion 30 (having, in theillustrated embodiment, a lower housing portion 30 a and an upperhousing portion 30 b) that is at least partially received in mountingarm 16 and that houses or supports the drive motors 20, 22, common gear24 and gear train 26. The housing portions may be configured or moldedto correspond to the shapes of the motor and to provide an inner cavityfor receiving the motors 20, 22, common gear 24, gear train 26 andattaching portion 28, and the two housing portions 30 a, 30 b may attachor mate together (such as via snap clasps 30 c or the like) to containor house the components therein, with the attaching portion exposed atan opening or aperture of the upper housing portion 30 b.

In the illustrated embodiment, actuator assembly 18 comprises rotarymotor 20 disposed within lower housing portion 30 a, with rotary motor22 disposed over or on top of rotary motor 20 (with a spacer or supportelement 32 disposed between motors 20, 22). However, although shown asbeing stacked atop one another, clearly the motors 20, 22 may beotherwise disposed at or in the housing portion (such as in aside-by-side arrangement or the like), while remaining within the spiritand scope of the present invention. Rotary motors 20, 22 compriseelectrically powered motors, which may be electrically connected to apower source of the vehicle, such as via electrical leads of the motorselectrically connecting to a vehicle wiring harness at the side of thevehicle and at the mirror mounting portion. The motors may beelectrically connected together such that a single electrical lead orwiring harness extends from the actuator for electrically connecting tothe vehicle wiring harness or vehicle electrical connector.

The rotary motors 20, 22 have rotationally driven output shafts 20 a, 22a with respective worm gears 20 b, 22 b attached to the output shafts 20a, 22 a. The output shafts 20 a, 22 a and worm gears 20 b, 22 b aregenerally parallel to one another, with the common gear 24 disposedbetween the worm gears 20 b, 22 b and having teeth that engage the teethof both worm gears 20 b, 22 b (with the worm gears engaging teeth of thecommon gear at diametrically opposed sides or regions of the commongear) so that, when the worm gears 20 b, 22 b are rotationally driven bymotors 20, 22, both worm gears 20 b, 22 b cooperatively rotate and drivethe common gear 24 about its axis, as discussed below. Optionally, otherarrangements of the motors and gears may be implemented, such asnon-parallel arrangements of the motors and worm gears, with the motoroutput gears engaging other regions of a common gear and cooperativelydriving the common gear, while remaining within the spirit and scope ofthe present invention.

In the illustrated embodiment, common gear 24 is connected to or joinedwith a worm gear 34 that is rotatable about a common axis of rotation orshaft 36 with common gear 24 when common gear 24 is rotated via motors20, 22. As shown in FIGS. 5-8, shaft 36 is generally transverse tooutput shafts 20 a, 22 a and worm gears 20 b, 22 b of drive motors 20,22. Worm gear 34 is disposed along and in toothed engagement with a ringgear 38 that is rotatably supported (such as via bearings 40) at thelower housing portion 30 a, so that ring gear 38 is rotatable about agenerally vertical axis of rotation when the actuator assembly andexterior rearview mirror assembly are normally mounted at a side of avehicle. The mirror head attaching portion 28 is fixedly attached at anattaching portion 42 (such as via ribs or projections of an actuatorattaching portion 28 b of attaching portion 28 being received at orpartially in slots or receiving portions 42 a of attaching portion, suchas can be seen with reference to FIG. 2) at ring gear 38, such thatrotation of ring gear 38 imparts a corresponding rotation of mirror headattaching portion 28 and thus of the mirror head portion 14 about thegenerally vertical axis of rotation and relative to the side of thevehicle equipped with the exterior rearview mirror assembly 10.

Optionally, the gear assembly or gear train 26 may include a clutchassembly (such as at the gear shaft 36), which may include a gearelement and biasing element or spring. Such a clutch assembly may allowfor slippage between the gear elements their shaft to allow for manualadjustment of the mirror head portion 14 relative to the mountingportion or arm 16. Clearly, the motor and gear assembly may comprisemore or less gear elements depending on the particular application ofthe actuator and the desired torque and speed applied during mirroradjustment.

Optionally, a plurality of travel stop pins 44 (such as three stop pinsas shown in FIGS. 2 and 6) may be disposed at the housing (such as atthe lower housing portion 30 a) to limit pivotal movement of theattaching portion 28. For example, the attaching plate or portion 28 mayhave a mating groove in and along which the stop pins travel when theattaching portion is rotated via operation of the motors 20, 22. Thegroove terminates at each end at a wall, which the respective stop pinengages to limit or stop further rotational or pivotal movement of theattaching portion relative to the housing.

Thus, the fixed housing 30 holds or supports or houses the motors 20, 22and gear train 26, and is fixedly mounted to or in the mirror baseportion 16. The rotatable attaching portion 28 of the actuator 18 isattached to the mirror head and is driven by the ring gear 38 of geartrain 26 to rotate the rotating attaching portion 28 and mirror head 14relative to the fixed housing 30 and mounting portion 16. Optionally,the mirror head portion 14 and/or reflective element 12 may be manuallyadjusted by a person or user via the slippage of the gear elements ofthe clutches.

Accordingly, the present invention provides a mirror actuator that isdisposed at a fixed portion of the mirror or of the vehicle, such as atthe mounting portion or base portion of the mirror assembly. Theactuator thus is fixedly mounted to the mirror base (which is fixedlyattached to the vehicle, such as at the door or fender area) and themirror head is attached to a rotatable mirror attaching portion of theactuator. The actuator includes two motors that cooperate or work intandem to rotatably drive a common gear element, which in turn rotatablydrives the gear train and the rotatable mirror attaching portion. Themotors are driven at the same speed and are synchronized so that bothmotors provide similar output to or driving of the common gear.

By providing two drive motors, the present invention substantiallyincreases the torque applied to the gear train and, thus, can fold orpivot a larger, heavier mirror head that would otherwise require asubstantially larger motor (which may be difficult to package at themirror mounting portion or base) or additional gear elements to increasethe torque output from a single drive motor (which may also be difficultto package at the mirror mounting portion or base and would add to thecomplexity and cost of the mirror actuator). The addition of a secondmotor that is substantially synchronized with a first motor nearlydoubles the output torque at the common gear (as compared to the outputof a single motor of the same power type), and may provide up to orgreater than about 90 percent to 95 percent more torque at the commongear, without requiring complex and costly gear trains with multiplegears to increase the torque from a single motor to a desired orappropriate torque at a mirror head.

Optionally, and desirably, the mirror system or actuator system mayoperate to deactivate the motors when the system or circuit determinesthat the mirror is in a stalled condition. For example, it is known tomeasure the current being drawn by a motor and if that current exceeds apredetermined trip point, a system or control may remove power from themotor. Such a trip point is frequently set to turn off the motor in theevent of a stall condition. A concern or potential shortcoming with thistype of circuit is that the motor and circuit parameters change withenvironment, particularly temperature. This change in system parametersaffects the operating point of the system such that the normal runcurrent can approach that of the stall current and can cause the shutoffcircuit to trip before a true stall condition is reached. Another issuewith such known shutoff circuits is that a shutoff circuit of this typemust be changed for each new trip current that needs to be detected.Thus, such shutoff circuits are not very flexible circuits wheremultiple systems with different loads need to be controlled.

Optionally, and desirably, the mirror system or actuator system mayoperate with a stall detection or run detection shutoff circuit (FIGS. 9and 10), whereby the motors are deactivated when the system or circuitdetermines that the mirror is in a stalled condition. The presentinvention provides a shutoff circuit that is operable to detect ordetermine if a motor is moving when power is applied (rather thanmeasuring the current being drawn by the motor). As long as the motor ismoving, it is not in a stall condition and thus the system allows themotor to continue to run regardless of the current draw. Once the motorstops moving, the circuit detects the stall condition and removes powerfrom the motor. An advantage provided by this circuit is that the motoris allowed to run regardless of environmental conditions affecting thecurrent draw of the motor and thus the system can function in conditionswhere it may otherwise not be able to function. This circuit is alsoapplicable across a much wider range of implementations—up to thephysical limitations of the components—as it is not current drawdependent. Optionally, the system may also have a current draw thresholdlevel at which the motor is shut off (to protect the motor), but thatmay be a significantly higher level than typical shutoff circuits.

When a DC motor moves (or, in other words, when the motor rotationallydrives and rotationally moves the output shaft of the motor), highcurrent ripples are created when the motor brushes cross adjacentcommutator bars. These current ripples in turn cause voltage spikes onthe drive signal. During a stall condition, the brushes do not cross thecommutator bars so these spikes do not exist. Thus, and as shown inFIGS. 9 and 10, when a drive voltage (shown for example as a DC voltagesource in FIG. 10) is applied to the circuit, the normally closedswitch, when closed, allows current to flow through the motor for atleast the amount of time configured by the delay element. For example,and with reference to FIG. 10, current may flow from the positiveterminal at the drive voltage and to the motor (via the diode thatbypasses the upstream normally closed switch) and through the motor andthrough the downstream normally closed switch to ground or the negativeterminal of the DC voltage source (see the solid arrows in FIG. 10),while voltage spikes that occur during such operation may be captured bythe DC blocking capacitor and a signal indicative of these spikes (seethe dashed arrows in FIG. 10) is used to control the delay element andnormally closed switch.

During operation of the actuator, the DC blocking capacitor captures thevoltage spikes created by the commutation of the motor during movement(or during rotation of the output shaft of the motor during operation ofthe motor). These spikes are amplified to a usable level and passedthrough a band-pass filter designed to set the lower threshold of motorspeed before the shutoff activates as well as remove spurious highfrequency noise. For example, the band-pass filter may have a lowerthreshold level that represents a selected or appropriate lowermostspeed at which the motor can run before the shutoff circuit opens andstops the motor. While the signal is within the designed or selectedfrequency band, the delay element is repeatedly reset and the switchremains closed (thus allowing for normal operation of the motor andactuator). If the signal frequency is outside the selected frequencyband (in other words, if the motor is not moving or is slowly moving ata speed where the frequency of the signal is reduced or below theselected lower threshold frequency), the delay expires and the switch isopened (thus stopping operation of the motor and actuator) and remainsopened until the applied voltage is removed and the circuit is reset.

In the illustrated embodiment, the circuit provides bi-directionalprotection for the motor and can function when current is flowing ineither direction from the power source. A diode is used to bypass therun detection circuitry on the high-side of the drive signal to providesuch bi-directional protection for the motor. For example, if thehigh-side of the drive signal is at the upper side of the power source,the system functions as described above, and if the high-side of thedrive signal is at the lower side of the power source, the circuit flowis reversed.

Optionally, and with reference to FIGS. 11-17, an actuator assembly 118includes at least two electrical drive motors 120, 122, which arecooperatively operable to rotatably drive a ring gear 138 via a geartrain or gear assembly 126 to pivot a mirror head portion about agenerally vertical pivot axis to adjust the mirror head portion relativeto the mounting arm, such as in a similar manner as discussed above withrespect to actuator 18. Actuator assembly 118 includes a housing portion130 (having, in the illustrated embodiment, a lower housing portion 130a and an upper housing portion 130 b), which may be at least partiallyreceived in the mounting arm of the mirror assembly and which houses orsupports the drive motors 120, 122, ring gear 138 and gear train 126.The housing portions may be configured or molded to correspond to theshapes of the motor and to provide an inner cavity for receiving themotors 120, 122, common gear 124, gear train 126 and attaching portion128, and the two housing portions 130 a, 130 b may attach or matetogether (such as via snap clasps or the like) to contain or house thecomponents therein, with the attaching portion 128 disposed at anopening or aperture of the upper housing portion 130 b (andinterconnected with ring gear 138, such that pivotal movement of ringgear 138 about its axis imparts a corresponding pivotal movement ofattaching portion 128 relative to the housing 130).

In the illustrated embodiment, rotary motor 120 is disposed within lowerhousing portion 130 a, and rotary motor 122 is disposed at an oppositeside of the ring gear 138 from rotary motor 120. The rotationally drivenoutput shafts 120 a, 122 a of rotary motors 120, 122 have respectiveworm gears 120 b, 122 b and are generally parallel to one another. Agear assembly 132, 133 is disposed between the respective worm gears 120b, 122 b and the ring gear 138. In the illustrated embodiment, the gearassemblies 132, 133 comprise a shaft 132 a, 133 a that is pivotallymounted at the housing, with a ring gear 132 b, 133 b at or near one endof the shaft that engages the respective worm gear 120 b, 122 b, andwith a worm gear 132 c, 133 c at or near the other end of the shaft thatengages a respective portion of the ring gear 138 (with the worm gearsengaging teeth of the ring gear at diametrically opposed sides orregions of the ring gear). The shafts 132 a, 133 a may be pivotallymounted at the lower housing portion 130 a via bearings 132 d, 133 dthat are received in recesses or receiving portions established ormolded in the lower housing portion (which may comprise an injectionmolded polymeric housing portion or the like). Thus, when the worm gears120 b, 122 b are rotationally driven by motors 120, 122, both worm gears120 b, 122 b rotate their respective gear assemblies 132, 133, which inturn cooperatively rotate and drive the ring gear 138 about its axis.

Similar to the actuator 18, discussed above, ring gear 138 is rotatablysupported (such as via bearings 140) at the lower housing portion 130 a,so that ring gear 138 is rotatable about a generally vertical axis ofrotation when the actuator assembly and exterior rearview mirrorassembly are normally mounted at a side of a vehicle. The mirror headattaching portion 128 is fixedly attached at an attaching portion 142 atring gear 138 (such as via ribs or projections of an actuator attachingportion of attaching portion 128 being received at or partially in slotsor receiving portions 142 a of ring gear 138), such that rotation ofring gear 138 imparts a corresponding rotation of mirror head attachingportion 128 and thus of the mirror head portion about the generallyvertical axis of rotation and relative to the side of the vehicleequipped with the exterior rearview mirror assembly.

Optionally, the actuator and gear assembly or gear train may include aclutch assembly, which may include a gear element and biasing element orspring. Such a clutch assembly may allow for slippage between the gearelements to allow for manual adjustment of the mirror head portionrelative to the mounting portion or arm of the mirror assembly.Optionally, a pair of travel stop pins 144 may be disposed at thehousing (such as at the lower housing portion 130 a) to limit pivotalmovement of the attaching portion 128. The attaching plate or portion128 has a mating groove in and along which the stop pins travel when theattaching portion is rotated via operation of the motors 120, 122. Thegroove terminates at each end at a wall, which the respective stop pinengages to limit or stop further rotational or pivotal movement of theattaching portion relative to the housing. In the illustratedembodiment, the stop pins 144 are received in receiving portions of thelower housing 130 a and a spring or biasing element 145 is also disposedin the receiving portions to bias or urge the pins towards and intoengagement with the attaching portion to maintain engagement with theattaching portion during operation of the actuator.

Thus, the dual motor actuator of the present invention includes twomotors (but optionally may include three or more motors) engaged withand driving a common gear. The dual motor arrangement provides increasedoutput torque of the actuator while maintaining the tooth load on thefirst gear the same as for a single actuator motor (and thus allows foruse of typical drive gears without having to implement stronger morerobust gears to handle increased output torque of a larger singlemotor). The actuator of the present invention thus may be used in anymirror application that requires high torque output to pivot largeand/or heavy mirror head portions, such as for trailer towing power foldmirror assemblies and/or power extend mirror assemblies and/or the like.

The actuator assembly or device and its motors and gears may compriseany suitable rotational driving device or means, such as rotationaldriving devices similar to those used in power fold mirror applications(such as the types described in U.S. Pat. Nos. 7,314,285; 7,267,449;7,159,992; 7,093,946; 6,312,135; 6,243,218; and 5,703,731, which arehereby incorporated herein by reference in their entireties, and mayutilize aspects of the indexing and control pivoting of the mirrorsdescribed in U.S. Pat. No. 5,703,731) or the like, or may such aspivotal or rotational driving devices or actuators similar to those usedin reflective element actuators (such as the types described in U.S.Pat. Nos. 7,722,199; 7,080,914; 7,073,914; 7,104,663; 6,916,100;6,755,544; 6,698,905; 6,685,864; 6,467,920; 6,362,548; 6,243,218;6,229,226; 6,213,612; 5,986,364 and 5,900,999, and/or U.S. patentapplication Ser. No. 11/504,353, filed Aug. 15, 2006 and published Jan.4, 2007 as U.S. Publication No. 2007/002477, which are herebyincorporated herein by reference in their entireties). Optionally, theactuator may utilize aspects of the actuators described in U.S. patentapplication Ser. No. 13/023,747, filed Feb. 9, 2011, now U.S. Pat. No.8,915,601, and/or U.S. provisional applications, Ser. No. 61/705,876,filed Sep. 26, 2012; Ser. No. 61/697,554, filed Sep. 6, 2012; Ser. No.61/665,509, filed Jun. 28, 2012; Ser. No. 61/664,438, filed Jun. 26,2012; Ser. No. 61/647,179, filed May 15, 2012; Ser. No. 61/614,877,filed Mar. 23, 2012; and Ser. No. 61/601,756, filed Feb. 22, 2012, whichare all hereby incorporated herein by reference in their entireties.

Optionally, mirror reflector or reflective element may comprise agenerally planar glass mirror substrate or substrates (or may comprise abent or curved substrate or substrates) and may comprise a variablyreflective, electro-optic reflective element (having a front and rearsubstrate with an electro-optic medium sandwiched therebetween) or asingle substrate reflective element (such as a planar or curved or bentglass reflective element), while remaining within the spirit and scopeof the present invention. The reflective element has a reflector coatingfor reflecting light incident thereon to provide a rearward field ofview to the driver of the vehicle. The reflector coating is disposed atan appropriate surface of the reflective element.

For example, the reflective element of the rearview mirror assembly maycomprise an electro-optic or electrochromic reflective element or cell,such as an electrochromic mirror assembly and electrochromic reflectiveelement utilizing principles disclosed in commonly assigned U.S. Pat.Nos. 7,626,749; 7,338,177; 7,274,501; 7,255,451; 7,195,381; 7,184,190;7,004,592; 6,690,268; 6,420,036; 6,286,965; 6,196,688; 6,178,034;6,154,306; 6,065,840; 6,002,544; 5,910,854; 5,751,489; 5,724,187;5,668,663; 5,610,756; 5,567,360; 5,535,056; 5,525,264; 5,406,414;5,253,109; 5,151,816; 5,142,407; 5,140,455; 5,117,346; 5,076,673;5,073,012; and/or 4,712,879, and/or U.S. patent application Ser. No.11/226,628, filed Sep. 14, 2005 and published Mar. 23, 2006 as U.S.Publication No. US-2006-0061008, and/or PCT Application No.PCT/US2010/029173, filed Mar. 30, 2010 and published Oct. 7, 2010 asInternational Publication No. WO 2010/114825, and/or PCT Application No.PCT/US10/32017, filed Apr. 22, 2010 and published Oct. 28, 2010 asInternational Publication No. WO 2010/124064, and/or PCT Application No.PCT/US10/51741, filed Oct. 7, 2010 and published Apr. 14, 2011 asInternational Publication No. WO 2011/044312, which are all herebyincorporated herein by reference in their entireties, and/or asdisclosed in the following publications: N. R. Lynam, “ElectrochromicAutomotive Day/Night Mirrors”, SAE Technical Paper Series 870636 (1987);N. R. Lynam, “Smart Windows for Automobiles”, SAE Technical Paper Series900419 (1990); N. R. Lynam and A. Agrawal, “Automotive Applications ofChromogenic Materials”, Large Area Chromogenics: Materials and Devicesfor Transmittance Control, C. M. Lampert and C. G. Granquist, EDS,Optical Engineering Press, Wash. (1990), which are hereby incorporatedby reference herein in their entireties. Optionally, the reflectiveelement may include a perimeter metallic band, such as the typesdescribed in U.S. Pat. Nos. 7,626,749; 7,255,451; 7,274,501 and7,184,190; and/or U.S. patent application Ser. No. 11/226,628, filedSep. 14, 2005 and published Mar. 23, 2006 as U.S. Publication No.US-2006-0061008, which are all hereby incorporated herein by referencein their entireties. Optionally, the reflective element may includeindicia formed at and viewable at the reflective element, such as byutilizing aspects of the reflective elements described in U.S. Pat. No.7,626,749, which are all hereby incorporated herein by reference intheir entireties.

Optionally, the reflective element may comprise a single substrate witha reflective coating at its rear surface. The mirror assembly thus maycomprise a prismatic mirror assembly or planar or non-planar mirror orother mirror having a single substrate reflective element, such as amirror assembly utilizing aspects of the mirror assemblies described inU.S. Pat. Nos. 7,289,037; 7,249,860; 6,318,870; 6,598,980; 5,327,288;4,948,242; 4,826,289; 4,436,371; and 4,435,042, which are herebyincorporated herein by reference in their entireties. Optionally, thereflective element may comprise a conventional prismatic or flatreflective element or prism, or may comprise a prismatic or flatreflective element of the types described in U.S. Pat. Nos. 7,184,190;7,249,860; 7,255,451; 7,274,501; 7,289,037; 7,338,177; 7,420,756; and/or7,626,749, which are all hereby incorporated herein by reference intheir entireties.

Optionally, the reflective element may comprise a bent, wide-anglemirror reflector rather than a flat mirror reflector. If a bent,wide-angle mirror reflector is used, it is preferable that the mirrorreflector comprise a glass substrate coated with a bendable reflectorcoating (such as of silicon as described in U.S. Pat. Nos. 6,065,840;5,959,792; 5,535,056 and 5,751,489, which are hereby incorporated byreference herein in their entireties).

Optionally, the mirror assembly and/or reflective element may include awide angle reflector or blind spot viewing aid or the like to provide awide angle field of view of the blind spot area at the side of thevehicle to the driver of the vehicle. Optionally, for example, themirror assembly may utilize aspects of the reflectors or assembliesdescribed in U.S. Pat. Nos. 7,748,856; 7,255,451; 7,195,381; 6,717,712;6,315,419; 7,097,312; 6,522,451; and/or 7,126,456, and/or U.S. patentapplication Ser. No. 12/187,725, filed Aug. 27, 2008, now U.S. Pat. No.8,786,704, which are hereby incorporated herein by reference in theirentireties.

Optionally, the mirror head portion or mirror casing or a back plate mayinclude a perimeter framing portion or bezel portion that extends aroundthe perimeter edges of the reflective element to support the reflectiveelement and frame the reflective element at the mirror assembly (such asby utilizing aspects of the mirror assemblies described in U.S. Pat. No.7,581,859, which is hereby incorporated herein by reference in itsentirety). The perimeter bezel portion may be narrow or small dependingon the particular application of the reflective element and mirrorreflector sub-assembly. Optionally, the mirror reflective element maycomprise a bezelless or frameless reflective element (such as the typesdescribed in U.S. Pat. Nos. 7,626,749; 7,184,190 and/or 7,255,451;and/or U.S. patent application Ser. No. 11/226,628, filed Sep. 14, 2005and published Mar. 23, 2006 as U.S. Publication No. US-2006-0061008,which are hereby incorporated herein by reference in their entireties),whereby the back plate may not include a perimeter framing portion orbezel portion around the perimeter of the reflective element.

Optionally, and desirably, the mirror assembly may include a heaterelement that is disposed at or established at the rear surface of thereflective element to reduce fogging of the reflective element. Theheater pad or element at the rear surface of the glass substrate mayprovide an anti-fogging of de-fogging feature to the exterior mirrorassembly, and may utilize aspects of the heater elements or padsdescribed in U.S. Pat. No. 7,400,435 and/or PCT Application No.PCT/US07/82099, filed Oct. 22, 2007 and published on May 2, 2008 asInternational Publication No. WO 2008/051910, and/or U.S. patentapplication Ser. No. 13/111,407, filed May 19, 2011 and published Nov.24, 2011 as U.S. Pub. No. US-2011-0286096, which are hereby incorporatedherein by reference in their entireties). The heater element may includeelectrical contacts that extend rearward therefrom and through anaperture of attaching portion of back plate for electrical connection toa wire harness or connector of the mirror assembly, or the back plateand/or heater pad may include suitable electrical connectors andconnections incorporated therein (such as by utilizing aspects of themirror assembly described in U.S. Pat. No. 7,400,435, which is herebyincorporated herein by reference in its entirety) for electricallyconnecting the heater pad (or other suitable electrical connectors maybe utilized, such as electrical leads or wire harnesses or pigtails orother separate connectors or cables or the like).

Optionally, the mirror assembly may include an indicator or illuminationsource (such as for backlighting an indicator or indicia at thereflective element), such as by utilizing aspects of the mirrorassemblies described in U.S. Pat. Nos. 8,058,977; 7,855,755; 7,492,281;6,919,796; 6,198,409; 5,929,786; and 5,786,772, which are herebyincorporated herein by reference in their entireties. Optionally, otherillumination sources may be included, such as for illuminating a sideregion at or adjacent to the vehicle or illuminating other regionsexterior of the vehicle, such as by utilizing aspects of the mirrorassemblies described in U.S. Pat. Nos. 6,669,267; 6,969,101; 6,824,281;and/or 7,188,963, and/or U.S. patent application Ser. No. 13/249,433,filed Sep. 30, 2011, now U.S. Pat. No. 8,764,256; and/or Ser. No.12/596,891, filed Oct. 21, 2009, now U.S. Pat. No. 8,333,492, which arehereby incorporated herein by reference in their entireties.

Optionally, the mirror assembly may include a blind spot indicatorand/or a turn signal indicator, such as an indicator or indicators ofthe types described in U.S. Pat. Nos. 8,058,977; 7,944,371; 7,492,281;6,198,409; 5,929,786; and 5,786,772, which are hereby incorporatedherein by reference in their entireties. The signal indicator orindication module may include or utilize aspects of various lightmodules or systems or devices, such as the types described in U.S. Pat.Nos. 8,058,977; 7,626,749; 7,581,859; 7,255,451; 6,227,689; 6,582,109;5,371,659; 5,497,306; 5,669,699; 5,823,654; 6,176,602; and/or 6,276,821;and/or U.S. patent application Ser. No. 12/187,725, filed Aug. 7, 2008,now U.S. Pat. No. 8,786,704, which are hereby incorporated herein byreference in their entireties.

Such an indicator or indicators may function as a lane change assist(LCA) indicator or indicators and/or a blind spot indicator orindicators. Such blind spot indicators are typically activated when anobject is detected (via a side object or blind spot detection system orthe like such as described in U.S. Pat. Nos. 7,720,580; 7,492,281;7,038,577; 6,882,287; 6,198,409; 5,929,786; and 5,786,772, which arehereby incorporated herein by reference in their entireties) at the sideand/or rear of the vehicle (at the blind spot) and when the turn signalis also activated, so as to provide an alert to the driver of the hostvehicle that there is an object or vehicle in the lane next to the hostvehicle at a time when the driver of the host vehicle intends to moveover into the adjacent lane. Optionally, and alternately, the indicatoror indicators may function as a lane change assist indicator orindicators, where the host vehicle may be detected to be moving into anadjacent lane without the turn signal being activated, and an object orvehicle may be detected at the adjacent lane, whereby the LCA indicatoror indicators may be activated to provide an alert to the driver of thelane change to assist the driver in avoiding unintentional lane changesand/or lane changes when a vehicle or object is detected in the adjacentlane.

The blind spot indicators thus may be operable to provide an indicationto the driver of the host vehicle that an object or other vehicle hasbeen detected in the lane or area adjacent to the side of the hostvehicle. The blind spot indicator may be operable in association with ablind spot detection system, which may include an imaging sensor orsensors, or an ultrasonic sensor or sensors, or a sonar sensor orsensors or the like. For example, the blind spot detection system mayutilize aspects of the blind spot detection and/or imaging systemsdescribed in U.S. Pat. Nos. 7,881,496; 7,720,580; 7,038,577; 6,882,287;6,198,409; 5,929,786; and/or 5,786,772, and/or U.S. patent applications,and/or U.S. provisional application Ser. No. 60/618,686, filed Oct. 14,2004 by Laubinger, and/or of the reverse or backup aid systems, such asthe rearwardly directed vehicle vision systems described in U.S. Pat.Nos. 5,550,677; 5,760,962; 5,670,935; 6,201,642; 6,396,397; 6,498,620;6,717,610; 7,005,974; and/or 6,757,109, and/or of the automatic headlampcontrols described in U.S. Pat. Nos. 7,526,103; 5,796,094 and/or5,715,093, and/or of the rain sensors described in U.S. Pat. Nos.6,250,148 and 6,341,523, and/or of other imaging systems, such as thetypes described in U.S. Pat. Nos. 6,353,392 and 6,313,454, and/or PCTApplication No. PCT/US2010/25545, filed Feb. 16, 2010 and published Sep.2, 2010 as International Publication No. WO 2010/099416, and/or PCTApplication No. PCT/US10/47256, filed Aug. 31, 2010 and published Mar.10, 2011 as International Publication No. WO 2011/028686, which mayutilize various imaging sensors or imaging array sensors or cameras orthe like, such as a CMOS imaging array sensor, a CCD sensor or othersensors or the like, such as the types disclosed in commonly assigned,U.S. Pat. Nos. 7,339,149; 5,550,677; 5,760,962; 6,097,023 and 5,796,094,and/or PCT Application No. PCT/US2003/036177 filed Nov. 14, 2003,published Jun. 3, 2004 as PCT Publication No. WO 2004/047421, with allof the above referenced U.S. patents, patent applications andprovisional applications and PCT applications being commonly assignedand being hereby incorporated herein by reference in their entireties.

The signal indicator or indication module of the exterior rearviewmirror assembly may include or utilize aspects of various light modulesor systems or devices, such as the types described in U.S. Pat. Nos.7,581,859; 7,289,037; 6,227,689; 6,582,109; 5,371,659; 5,497,306;5,669,699; 5,823,654; 6,176,602; and/or 6,276,821, and/or U.S. patentapplication Ser. No. 11/226,628, filed Sep. 14, 2005 and published Mar.23, 2006 as U.S. Publication No. US-2006-0061008, and/or PCT ApplicationNo. PCT/US2006/018567, filed May 16, 2006 and published Nov. 23, 2006 asInternational Publication No. WO 2006/124682, which are herebyincorporated herein by reference in their entireties. Optionally, theillumination module may also comprise a ground illumination light orpuddle lamp, which provides downwardly directed illumination (and whichmay provide a back lit icon or indicia or logo or the like), such as byutilizing aspects of the illumination systems described in U.S. Pat.Nos. 5,371,659, 5,669,699, 5,823,654 and 5,497,305, and/or U.S. patentapplication Ser. No. 12/596,891, filed Oct. 21, 2009, now U.S. Pat. No.8,333,492, which are hereby incorporated herein by reference in theirentireties. Optionally, the illumination module or device of theexterior rearview mirror assembly may comprise a cornering light and apuddle lamp and turn signal light, and may have a wrap-around style turnsignal at the exterior mirror that may be fitted with a prism lens orthe like to project light in the appropriate direction and/or toward thetargeted location. The illumination module thus may include one or moreillumination sources and one or more lenses or optics or light pipes orthe like to distribute or direct illumination toward the appropriatetargeted areas.

Optionally, the exterior rearview mirror assembly may include a cameraor imaging sensor that may be part of a multi-camera system, such as anobject detection system or a surround view or “bird's eye view” displaysystem or a JapanVue™ vision system or the like (now common in exteriormirrors used in Japan where a video camera is located in the exteriormirror assembly at the side of a vehicle and viewing generallydownwardly to allow the driver of the vehicle to view on aninterior-cabin mounted video screen whether the likes of a child mightbe present in the blindzone to the side of the vehicle), such as byutilizing aspects of the vision systems described in PCT Application No.PCT/US10/25545, filed Feb. 26, 2010 and published on Sep. 2, 2010 asInternational Publication No. WO 2010/099416, and/or PCT Application No.PCT/US10/47256, filed Aug. 31, 2010 and published Mar. 10, 2011 asInternational Publication No. WO 2011/028686, and/or PCT Application No.PCT/US2011/062834, filed Dec. 1, 2011 and published Jun. 7, 2012 asInternational Publication No. WO 2012/075250, and/or PCT Application No.PCT/US2012/048993, filed Jul. 31, 2012 and published Feb. 7, 2013 asInternational Publication No. WO 2013/019795, and/or PCT Application No.PCT/US11/62755, filed Dec. 1, 2011 and published Jun. 7, 2012 asInternational Publication No. WO 2012-075250, and/or PCT Application No.PCT/CA2012/000378, filed Apr. 25, 2012 and published Nov. 1, 2012 asInternational Publication No. WO 2012/145822, and/or U.S. patentapplication Ser. No. 13/333,337, filed Dec. 21, 2011 and published Jun.28, 2012 as U.S. Publication No. US-2012-0162427, and/or U.S.provisional applications, Ser. No. 61/615,410, filed Mar. 26, 2012; Ser.No. 61/588,833, filed Jan. 20, 2012; Ser. No. 61/570,017, filed Dec. 13,2011; Ser. No. 61/568,791, filed Dec. 9, 2011; and/or Ser. No.61/559,970, filed Nov. 15, 2011, which are hereby incorporated herein byreference in their entireties).

Optionally, the mirror assembly may include one or more displays, suchas the types disclosed in U.S. Pat. Nos. 5,530,240 and/or 6,329,925,which are hereby incorporated herein by reference in their entireties,and/or display-on-demand or transflective type displays, such as thetypes disclosed in U.S. Pat. Nos. 7,370,983; 7,274,501; 7,255,451;7,184,190; 7,195,381; 6,690,268; 5,668,663 and/or 5,724,187, and/or inU.S. patent application Ser. No. 10/538,724, filed Jun. 13, 2005 andpublished Mar. 9, 2006 as U.S. Publication No. US-2006-0050018, whichare all hereby incorporated herein by reference in their entireties, ormay include or incorporate video displays or the like, such as the typesdescribed in U.S. Pat. Nos. 7,855,755; 7,777,611; 7,370,983; and/or6,690,268, which are hereby incorporated herein by reference in theirentireties.

Changes and modifications to the specifically described embodiments maybe carried out without departing from the principles of the presentinvention, which is intended to be limited only by the scope of theappended claims as interpreted according to the principles of patentlaw.

The invention claimed is:
 1. An exterior rearview mirror assembly for avehicle, said exterior rearview mirror assembly comprising: a mountingportion mountable at a side of a vehicle; a mirror head portionadjustably mounted at said mounting portion; a reflective element atsaid mirror head portion; an actuator operable to impart pivotalmovement of said mirror head portion relative to said mounting portionand about a generally vertical pivot axis to pivotally adjust saidmirror head portion relative to the side of the vehicle at which saidmounting portion is mounted; wherein said actuator comprises at leasttwo motors and wherein said at least two motors are operable in tandemto cooperatively rotatably drive a common drive gear of a gear system topivot said mirror head portion relative to said mounting portion;wherein said common drive gear is interconnected with an attachingportion of said actuator that attaches at one of said mirror headportion and said mounting portion, and wherein rotation of said commondrive gear imparts a rotation of said mirror head portion relative tosaid mounting portion; wherein output speeds of said at least two motorsare synchronized; and wherein, during operation of said actuator, ashutoff circuit is operable to determine rotational movement of a motoroutput shaft of at least one of said motors and, responsive to adetermination of the rotational movement being below a threshold speed,said shutoff circuit deactivates said at least one of said motorsirrespective of current draw by said at least one of said motors.
 2. Theexterior rearview mirror assembly of claim 1, wherein said at least twomotors comprise first and second motors, with said first motor having afirst output gear that engages said common drive gear and with saidsecond motor having a second output gear that engages said common drivegear.
 3. The exterior rearview mirror assembly of claim 2, wherein saidfirst and second output gears comprise worm gears disposed at outputshafts of said first and second motors.
 4. The exterior rearview mirrorassembly of claim 3, wherein said first and second output gears arearranged generally parallel to one another and engage teeth of saidcommon drive gear at opposite sides of said common drive gear.
 5. Theexterior rearview mirror assembly of claim 2, wherein said common drivegear is interconnected with a worm gear that rotates with said commondrive gear, and wherein said worm gear engages another drive gear thatis interconnected with an attaching portion of said actuator thatattaches at one of said mirror head portion and said mounting portion,and wherein rotation of said other drive gear imparts a rotation of saidmirror head portion relative to said mounting portion.
 6. The exteriorrearview mirror assembly of claim 1, wherein said at least two motorscomprise first and second motors, with said first motor having a firstoutput gear that engages a first gear element that rotatably drives saidcommon drive gear and with said second motor having a second output gearthat rotatably drives a second gear element that engages said commondrive gear.
 7. The exterior rearview mirror assembly of claim 6, whereinsaid first gear element is interconnected with a first worm gear thatrotates with said first gear element, and wherein said first worm gearengages said common drive gear and wherein said second gear element isinterconnected with a second worm gear that rotates with said secondgear element, and wherein said second worm gear engages said commondrive gear.
 8. The exterior rearview mirror assembly of claim 7, whereinsaid first and second worm gears engage said common drive gear atdiametrically opposite portions of said common drive gear.
 9. Theexterior rearview mirror assembly of claim 1, wherein, during operationof said actuator, said shutoff circuit determines rotational movement ofthe motor output shaft of both of said motors and, responsive to adetermination of the rotational movement being below a threshold speed,said shutoff circuit deactivates said motors irrespective of currentdraw by said motors.
 10. An exterior rearview mirror assembly for avehicle, said exterior rearview mirror assembly comprising: a mountingportion mountable at a side of a vehicle; a mirror head portionadjustably mounted at said mounting portion; a reflective element atsaid mirror head portion; an actuator operable to impart pivotalmovement of said mirror head portion relative to said mounting portionand about a generally vertical pivot axis to pivotally adjust saidmirror head portion relative to the side of the vehicle at which saidmounting portion is mounted; wherein said actuator comprises a firstmotor and a second motor and wherein said first and second motors areoperable in tandem to cooperatively rotatably drive a drive gear of agear system to pivot said mirror head portion relative to said mountingportion; wherein said drive gear is interconnected with an attachingportion of said actuator that attaches at one of said mirror headportion and said mounting portion, and wherein rotation of said drivegear imparts a rotation of said mirror head portion relative to saidmounting portion; wherein output speeds of said first and second motorsare synchronized; wherein, during operation of said actuator, a shutoffcircuit is operable to determine rotational movement of a first motoroutput shaft of said first motor; wherein, responsive to a determinationby said shutoff circuit that the rotational movement of said first motoroutput shaft of said first motor is below a threshold speed, saidshutoff circuit deactivates said first motor irrespective of currentdraw by said first motor; and wherein, responsive to a determination bysaid shutoff circuit that the rotational movement of said first motoroutput shaft of said first motor is above a threshold speed, saidshutoff circuit allows said first motor to continue to operateirrespective of current draw by said first motor.
 11. The exteriorrearview mirror assembly of claim 10, wherein said first motor rotatablydrives, via said first motor output shaft, a first output gear thatengages said drive gear and said second motor rotatably drives, via asecond motor output shaft, a second output gear that engages said drivegear.
 12. The exterior rearview mirror assembly of claim 11, whereinsaid first and second output gears comprise worm gears disposed atoutput shafts of said first and second motors.
 13. The exterior rearviewmirror assembly of claim 12, wherein said first and second output gearsare arranged generally parallel to one another and engage teeth of saiddrive gear at opposite sides of said drive gear.
 14. The exteriorrearview mirror assembly of claim 11, wherein said drive gear isinterconnected with a worm gear that rotates with said drive gear, andwherein said worm gear engages another drive gear that is interconnectedwith an attaching portion of said actuator that attaches at one of saidmirror head portion and said mounting portion, and wherein rotation ofsaid other drive gear imparts a rotation of said mirror head portionrelative to said mounting portion.
 15. The exterior rearview mirrorassembly of claim 10, wherein said shutoff circuit comprises a delayelement and wherein, when the rotational movement of said first motoroutput shaft of said first motor is determined to be above the thresholdspeed, said delay element is reset and said first motor continues tooperate, and wherein, when the rotational movement of said first motoroutput shaft of said first motor is determined to be below the thresholdspeed, said delay element expires and said first motor is deactivated.16. An exterior rearview mirror assembly for a vehicle, said exteriorrearview mirror assembly comprising: a mounting portion mountable at aside of a vehicle; a mirror head portion adjustably mounted at saidmounting portion; a reflective element at said mirror head portion; anactuator operable to impart pivotal movement of said mirror head portionrelative to said mounting portion and about a generally vertical pivotaxis to pivotally adjust said mirror head portion relative to the sideof the vehicle at which said mounting portion is mounted; wherein saidactuator comprises at least one motor and wherein said at least onemotor is operable to rotatably drive a drive gear of a gear system topivot said mirror head portion relative to said mounting portion;wherein said drive gear is interconnected with an attaching portion ofsaid actuator that attaches at one of said mirror head portion and saidmounting portion, and wherein rotation of said drive gear imparts arotation of said mirror head portion relative to said mounting portion;wherein, during operation of said actuator, a shutoff circuit isoperable to determine rotational movement of a motor output shaft ofsaid at least one motor; wherein, responsive to a determination by saidshutoff circuit that the rotational movement of said motor output shaftof said at least one motor is below a threshold speed, said shutoffcircuit deactivates said at least one motor irrespective of current drawby said at least one motor; and wherein, responsive to a determinationby said shutoff circuit that the rotational movement of said motoroutput shaft of said at least one motor is above a threshold speed, saidshutoff circuit allows said at least one motor to continue to operateirrespective of current draw by said at least one motor.
 17. Theexterior rearview mirror assembly of claim 16, wherein said shutoffcircuit determines the rotational movement of said motor output shaftresponsive to a signal indicative of voltage spikes created by thecommutation of said at least one motor during operation of said at leastone motor.
 18. The exterior rearview mirror assembly of claim 17,wherein said shutoff circuit comprises a delay element and wherein, whenthe signal is indicative of said motor output shaft being above thethreshold speed, said delay element is repeatedly reset and said atleast one motor continues to operate, and wherein, when the signal isindicative of said motor output shaft being below the threshold speed,said delay element expires and said at least one motor is deactivated.19. The exterior rearview mirror assembly of claim 16, wherein saidshutoff circuit provides bi-directional protection for said at least onemotor and is operable when current is flowing in either directionthrough said shutoff circuit.
 20. The exterior rearview mirror assemblyof claim 16, wherein said at least one motor comprises two motors andwherein one of said motors rotatably drives, via a first motor outputshaft, a first output gear that engages said drive gear and another ofsaid motors rotatably drives, via a second motor output shaft, a secondoutput gear that engages said drive gear, wherein said motors areoperable in tandem to cooperatively rotatably drive said drive gear of agear system to pivot said mirror head portion relative to said mountingportion, and wherein output speeds of said motors are synchronized.